Next month, Secretary of Defense Lloyd Austin must justify to Congress a 37% cost overrun in the Pentagon’s project to replace every nuclear missile in the land-based leg of the nuclear triad. He should make us all safer – and save the US public upwards of $100 billion – by cancelling the Sentinel intercontinental ballistic missile.
What cost overrun?
In January 2024, the Air Force notified Congress that Sentinel’s cost had increased by 37 percent, triggering a “critical” breach under the Nunn McCurdy Act —legislation to prevent major cost overruns in defense systems. A “critical” Nunn-McCurdy breach occurs when a program overruns its cost by at least 25 percent.
The total cost for Sentinel over the next ten years has now jumped to $132 billion, up from $96 billion, with the price of each missile increasing from $118 million to $162 million. A 2020 Department of Defense estimate put total program cost, including operations and support, at $264 billion for a planned 50-year life cycle. That number could now reach $300 billion. This still does not include the cost of a planned new warhead, which will add another $15 billion.
As Secretary of Defense, Austin must now investigate the Sentinel program, look for root causes of the breach, and determine whether the program should continue and, if so, what other programs should be cut to pay for it.
What is the Sentinel and do we really need it?
The LGM-35A Sentinel intercontinental ballistic missile (ICBM) is the planned replacement for the Minuteman III silo-based ICBM. The United States currently deploys 400 Minuteman III missiles in underground silos in five Plains states. First deployed in 1970, the Minuteman III has undergone extensive maintenance and upgrades, with the most recent, completed in 2015, totaling more than $7 billion to extend the missiles’ life to 2030.
The Air Force plans to purchase 642 new Sentinel missiles, of which it will deploy 400. The Sentinel will carry a new warhead, the W87-1, and will have the ability to carry multiple warheads. The new missiles are larger than the existing Minutemen III, requiring modification to silo facilities, adding to the costs and timeline of the program.
Billions of dollars over budget and years behind schedule, the Sentinel is a weapon the US does not need. Existing Minuteman III ICBMs are still fully capable, and their lives could be extended further. But ultimately, the U.S. would be much safer eliminating the land-based leg of the nuclear triad altogether.
Building costs
The Sentinel is also having a domino effect on other nuclear weapons programs, creating a perceived need to quickly build new plutonium pits—the explosive core of a modern nuclear weapons– as part of the new W87-1 warhead to be deployed on the Sentinel missiles. The W87-1 is the first new US warhead design in more than 30 years.
The Sentinel’s projected $132 billion price tag does not include costs for the new W87-1 warheads, or the plutonium pit production required for those warheads. If Sentinel were canceled or slowed it would reduce the need to produce new plutonium pits anytime soon. The first 800 pits to be produced are for new land-based missile warheads, the W87-1. The 80 plutonium pit per year production mandate from Congress was based in part on the need for these pits to be ready for deployment on the new Sentinel.
Like Sentinel, pit production is significantly over budget and behind schedule. Worse, building new pits for a new warhead signals the United States’ belief that nuclear weapons are still central to its security and it plans to maintain or grow its arsenal in the coming decades. Other countries will receive this message loud and clear and respond.
Behind schedule
According to a 2023 Government Accountability Office report, Sentinel won’t reach initial operational capability until 2030—a year later than the Department of Defense predicted in its own most recent report.
In March 2024, the Air Force confirmed that Sentinel’s initial flight test, originally scheduled for December 2023, will now be delayed until February 2026 due to “increased lead times” for guidance system components.
The Air Force says that supporting infrastructure is another factor in delays. The Sentinel program includes replacement and modification of launch facilities, new command and control facilities, and new missile alert facilities. This includes replacing about 7,500 miles of copper cables with modern fiber-optic cables.
Due to delays in the Sentinel program, the Air Force will now also need to keep some of the Minuteman III missiles operational for longer than planned, increasing maintenance and operational costs for those missiles and creating an overlap between the two systems that is likely to create additional complications and costs.
Unsafe and unnecessary
Beyond the vexing but solvable issues of cost and timeline, there are more important reasons to halt the Sentinel program.
Silo-based missiles are Cold War throwbacks. When the US first developed its nuclear arsenal, land-based missiles were more powerful and accurate than submarine-launched ballistic missiles and commanders were also less confident in their ability to maintain secure communication with submarines at sea. This is no longer the case—submarine-based missiles are now as accurate and powerful as land-based missiles and communications with submarines are reliable and secure; this has been true for decades.
Silo-based missiles also present a greater risk of mistaken use than other legs of the nuclear triad. Because they sit in fixed, known, positions they are vulnerable to attack, and land-based missiles are kept on hair-trigger alert, ready to be launched within minutes of the president’s order to do so.
Originally this was out of fear that a surprise Soviet attack could wipe out US silo-based missiles before they could be launched. Because Russian ICBMs could reach the US in just 30 minutes, the US developed a highly time-compressed process that leaves the president with less than ten minutes to decide whether to launch land-based missiles in response. Submarine-launched ballistic missiles—nearly impossible to target while at sea—do not face the same issue.
What happens now?
Austin has until July 10 to certify the continuing need for Sentinel, even given its delays and huge cost overruns. At an April 30 hearing, a Pentagon official told Congress that the review process for Sentinel is about halfway done and that no outcomes had been ruled out, including cancellation. The Air Force, however, seems confident that this will not happen, with one official declaring that “Sentinel will be funded,” and another saying that “there won’t be a decision made that we can live without it.” The latest news is that the Air Force has fired the head of the Sentinel program due to “a loss of confidence” in the program’s management, although they claim his firing is not directly related to the Nunn-McCurdy breach.
With Russia continuing to rattle its nuclear saber and increasingly hostile US rhetoric about the nuclear threat from China, it is unlikely that the Secretary of Defense Austin will pull the plug on Sentinel. But Congress should take this opportunity to consider whether doubling down on land-based missiles, which are increasingly costly, vulnerable and unnecessary, is really the right move, or if we wouldn’t all be better off finally admitting that their time has passed.